VINs were first used in 1954.[1] From 1954 to 1981, there was no accepted standard for these numbers, so different manufacturers used different formats.

In 1981, the National Highway Traffic Safety Administration of the United States standardized the format.[1] It required all over-the-road-vehicles sold to contain a 17-character VIN, which does not include the letters I (i), O (o), or Q (q) (to avoid confusion with numerals 1 and 0).

There are vehicle history services in several countries that can help potential car owners use VINs to find lemons and branded vehicles. See the used car article for a list of countries where this service is available.

The first three characters uniquely identify the manufacturer of the vehicle using the world manufacturer identifier or WMI code. A manufacturer who builds fewer than 500 vehicles per year uses a 9 as the third digit, and the 12th, 13th and 14th position of the VIN for a second part of the identification. Some manufacturers use the third character as a code for a vehicle category (e.g., bus or truck), a division within a manufacturer, or both. For example, within 1G (assigned to General Motors in the United States), 1G1 represents Chevrolet passenger cars; 1G2, Pontiac passenger cars; and 1GC, Chevrolet trucks.

The first character of the WMI is the region in which the manufacturer is located. In practice, each is assigned to a country of manufacture, although in Europe the country where the continental headquarters is located can assign the WMI to all vehicles produced in that region (Example: Opel/Vauxhall cars whether produced in Germany, Spain, the United Kingdom or Poland carry the W0L WMI because Adam Opel AG is based in Rüsselsheim, Germany).

In the notation below, assume that letters precede numbers and that zero is the last number. For example, 8X-82 denotes 8X, 8Y, 8Z, 81, 82. In particular this does not include 80.

The 4th to 8th positions in the VIN are the vehicle descriptor section or VDS. This is used, according to local regulations, to identify the vehicle type, and may include information on the automobile platform used, the model, and the body style. Each manufacturer has a unique system for using this field. Most manufacturers since the 1980s have used the 8th digit to identify the engine type whenever there is more than one engine choice for the vehicle. Example: for the 2007 Chevrolet Corvette U= 6.0L V8, E= 7.0L V8.

The 10th to 17th positions are used as the vehicle identifier section or VIS. This is used by the manufacturer to identify the individual vehicle in question. This may include information on options installed or engine and transmission choices, but often is a simple sequential number. In North America, the last five digits must be numeric.

One consistent element of the VIS is the 10th digit, which is required worldwide to encode the model year of the vehicle. Besides the three letters that are not allowed in the VIN itself (I, O and Q), the letters U and Z and the digit 0 are not used for the model year code. Note that the year code is the model year for the vehicle.

The year 1980 was encoded by some manufacturers, especially General Motors and Chrysler, as "A" (since the 17-digit VIN wasn't mandatory until 1981, and the "A" or zero was in the manufacturer's pre-1981 placement in the VIN), yet Ford and AMC still used a zero for 1980. Subsequent years increment through the allowed letters, so that "Y" represents the year 2000. 2001 to 2009 are encoded as the digits 1 to 9, and subsequent years are encoded as "A", "B", "C", etc.

Code

Year

Code

Year

Code

Year

Code

Year

Code

Year

Code

Year

A =

1980

L =

1990

Y =

2000

A =

2010

L =

2020

Y =

2030

B =

1981

M =

1991

1 =

2001

B =

2011

M =

2021

1 =

2031

C =

1982

N =

1992

2 =

2002

C =

2012

N =

2022

2 =

2032

D =

1983

P =

1993

3 =

2003

D =

2013

P =

2023

3 =

2033

E =

1984

R =

1994

4 =

2004

E =

2014

R =

2024

4 =

2034

F =

1985

S =

1995

5 =

2005

F =

2015

S =

2025

5 =

2035

G =

1986

T =

1996

6 =

2006

G =

2016

T =

2026

6 =

2036

H =

1987

V =

1997

7 =

2007

H =

2017

V =

2027

7 =

2037

J =

1988

W =

1998

8 =

2008

J =

2018

W =

2028

8 =

2038

K =

1989

X =

1999

9 =

2009

K =

2019

X =

2029

9 =

2039

On April 30, 2008, the US National Highway Traffic Safety Administration adopted a final rule amending 49 CFR Part 565, "so that the current 17 character vehicle identification number (VIN) system, which has been in place for almost 30 years, can continue in use for at least another 30 years", in the process making several changes to the VIN requirements applicable to all motor vehicles manufactured for sale in the United States. There are three notable changes to the VIN structure that affect VIN deciphering systems:

The make may only be identified after looking at positions 1–3 and another position, as determined by the manufacturer in the second section or 4–8 segment of the VIN.

In order to identify exact year in passenger cars and multipurpose passenger vehicles with a GVWR of 10,000 or less, one must read position 7 as well as position 10. For passenger cars, and for multipurpose passenger vehicles and trucks with a gross vehicle weight rating of 10,000 lb (4,500 kg) or less, if position 7 is numeric, the model year in position 10 of the VIN refers to a year in the range 1980–2009. If position 7 is alphabetic, the model year in position 10 of VIN refers to a year in the range 2010–2039.

The model year for vehicles with a GVWR greater than 10,000 lb (4,500 kg), as well as buses, motorcycles, trailers and low speed vehicles may no longer be identified within a 30-year range. VIN characters 1–8 and 10 that were assigned from 1980–2009 can be repeated beginning with the 2010 model year.

Another consistently-used element (which is compulsory in North America) is the use of the 11th character to encode the factory of manufacture of the vehicle. Although each manufacturer has its own set of plant codes, the location in the VIN is standardized.

In the United States, the 12th to 17th digits are the vehicle's serial or production number. This is unique to each vehicle and every manufacturer uses their own sequences as there is no fixed standard for this number.

Check digit validation is compulsory for cars made in North America, as well as for all vehicles destined for sale in North America. It also may be used voluntarily by manufacturers who choose to do so for vehicle destined for markets where it is not required. In particular, it does not apply to vehicles, not destined for the North American market, produced by the following manufacturers: Citroën, BMW, Renault, Audi, Korean Chevrolets, Fiat and European Fords, among others.[citation needed]

If trying to validate a VIN with a check digit, first either: (a) remove the check digit for the purpose of calculation; or (b) utilize the multiplicative property of zero in the weight to cancel it out. The original value of the check digit is then compared with the calculated value. If the two values do not match (and there was no error in the calculation), then there is a mistake in the VIN. However, a match does not prove the VIN is correct because there is still a 1 in 11 chance of any two distinct VINs having a matching check digit: an example of this would be the valid VINs 5GZCZ43D13S812715 (correct with leading five) and SGZCZ43D13S812715 (incorrect with leading character "S"). Note that the VINs in the Porsche image, WP0ZZZ99ZTS392124, and the GM-T body image, KLATF08Y1VB363636, do not pass the North American check digit verification.

Transliteration consists of removing all of the letters, and substituting them with their appropriate numerical counterparts. These numerical alternatives (based on IBM's EBCDIC) can be found in the following chart. I, O and Q are not allowed, and can not exist in a valid VIN; for the purpose of this chart, they have been filled in with N/A (not applicable). Numerical digits use their own values.

The remainder is the check digit. If the remainder is 10 then the check digit is X. In this example the remainder is 10, so the check digit is transliterated into X.

With a check digit of 'X' the VIN: 1M8GDM9A_KP042788 is written as: 1M8GDM9AXKP042788.

Straight-ones (seventeen consecutive '1's) will suffice the check-digit. This is because a value of one, multiplied against 89 (sum of weights), is still 89. And 89 divided by 11 is 8 with the remainder being the fraction "1 over 11," thus 1 is the check digit. This is an easy way to test a VIN-check algorithm.

VINs may be optically read with barcode scanners or digital cameras, or digitally read via OBD-II in newer vehicles. There are smartphone applications that can pass the VIN to websites to decode the VIN.